house-building.com NEWSLETTER
#213
Residential Building: Geothermal Energy for New Home Construction
James Todd.
March, 2003
Beginning with this edition, newsletters will now be archived
online at: http://www.house-building.com/newsletters/newsletters.html
CONTENTS:
- Geothermal Energy Systems: Is there one in your future
Courtesy of Franklin Energy
Systems
- The 10 most common mistakes in the building of
a new home
Guest article, by Chris McMinn, Professional Cost Analyst
and Consultant
- Useful Links
- Thought for the Day
- Subscription Information
Please forward this newsletter to
anyone whom you think may be interested!
1. Geothermal Energy
Systems
With oil prices approaching $40 per barrel, gasoline $2/gallons,
and heating
oil well over $1.50 it is prudent to examine alternatives
that could possible save you significant dollars over the
long haul of owning and living in your house. Geothermal
energy is one such alternative.
Americans usually rely on two familiar systems to heat
homes or buildings: fuel-powered furnaces or boilers (which
burn gas, oil, or propane) and electric-powered air-source
heat pumps or baseboard radiant heat. However, these traditional
systems present two drawbacks. First, even highly efficient
models pollute the environment because fuel must be burned
to produce heat. Second, energy prices are rising. Accordingly,
people want cost-effective long-term heating and cooling
options. Geothermal systems are one such option: they are
being installed in homes, businesses, and schools across
the country.
Geothermal 101
What is a "geothermal" system? It takes advantage
of the Earth’s ability to store vast amounts of heat
in the soil ("geo" means earth and "thermal" refers
to heat). This heat energy is maintained at a constant
temperature (50°F to 70°F depending on latitude)
in the soil and near-surface rocks. In Wisconsin, the soil
maintains a 50°F temperature beginning approximately
four feet down, well past the winter frost line.
Geothermal heating systems, also called ground-source heat
pumps, "capture" this steady supply of heat energy
and "move" it from the Earth and through a home
or building. Basically, once installed, a home or building
owner will use much less energy, save money each month,
and reduce the amount of pollution produced by fossil fuel
systems. In Wisconsin, for example, two school districts
recently began installing geothermal systems at area high
schools. In both Fond du Lac and Evansville, district administrators
were "sold" on this technology’s energy
efficiency and its ability to yield long-term cost savings.
Schools across Wisconsin and the country have faced skyrocketing
energy bills and they are searching for cost-effective
alternatives. Geothermal systems represent a proven option.
In addition, they utilize a renewable energy source—the
Earth’s naturally-occuring heat energy.
How Ground Source Heat Pumps Work
A heat pump is a mechanical device that transfers heat
from one source to another. Ground-source units pull heat
from the earth and transfer it to homes or buildings. Heat
pumps (despite their name) can provide both heating and
cooling. The cooling process is simply the reverse of the
heating process: heat is taken out of a building and returned
to the Earth.
Typical ground-source heat pumps transfer heat using a
network of tubes, called "closed loops." Basically,
the loops are filled with either water, refrigerant or
an anti-freeze solution. They run through the ground in
the vicinity of a building and the liquid absorbs the Earth’s
heat energy. Then, this warmed liquid is pumped back through
the system into the building. This process provides heat
to the building space. Once the fluid passes through the
building and transfers its energy, it flows through the
loop system back to the Earth and the process repeats itself.
In the summertime, these systems "reverse" into
cooling mode. Technically, the system does not "run
backwards." Instead, a series of valves enables the
system to switch the "hot" side and the "cold" side.
The heat from the building is transferred to the liquid
in the loop and this liquid is pumped back into the ground.
When the ground source heat pump is in cooling mode, it
usually has an excess of warmed liquid in the system. This
liquid can heat water for the building and basically eliminate
the use of the hot water heater during the summer months.
Saving Energy
Ground-source heat pumps can use 25%-70% less electricity
than conventional electric heating and cooling systems.
First, in winter heating mode, a ground-source heat pump
uses energy from the Earth to provide heat, whereas air-source
heat pump try to extract the last bits of heat energy out
of cold winter air. Because of the long, cold Wisconsin
winters, air-source heat pumps are not effective or efficient.
Second, ground-source heat pumps are more energy efficient
than conventional electric heaters because they maximize
the thermodynamic advantage of a heat transfer fluid. This
benefit enables the ground source heat pump to produce
more heat energy output than electric energy input. Conventional
electric heaters on the other hand don’t quite produce
as much heat output as electric input. (Under some conditions,
a ground source heat pump cannot meet the required heating
needs. In these cases, supplemental heat must be provided
from another source–usually conventional electric
units.)
Third, during the summer, the ground source heat pump "reverses" into
cooling mode. This fact makes the ground-source heat pump
more energy efficient for cooling than a traditional air
conditioner.
Finally, when a desuperheater is installed, energy from
the ground source heat pump can be transferred to the hot
water tank. As a result, building occupants receive "free" hot
water in the summer and very low-cost hot water in the
winter.
Saving Money
A ground source heat pump system, including the underground
loops, costs about $2,500 per ton of capacity, or roughly
$7,500 for a 3-ton unit (typical size for new home construction).
Approximately half of this cost is related to the geothermal
loop configuration. It can be expected to last from 20
to 30 years with minimal maintenance. A conventional heating
and cooling system costs up to $4,000.
At first glance, this price difference of $3,500 may seem
impractical and too costly. However, buyers must carefully
consider monthly energy costs over the life of the equipment
when making a decision. As the school administrators in
Fond du Lac and Evansville learned this past year, rising
energy prices can destroy annual budgets and geothermal
systems are a good way to minimize future price shocks.
Since these systems use from 25% to 50% less energy than
conventional systems, users will spend less on their monthly
energy bills. In fact, many homeowners could spend from
$35 to $70 less per month, meaning that most ground source
systems will "pay for themselves" in 2 to 10
years. The additional cost of $3,500 will be recovered
from the monthly energy savings. After the "payback" period,
the owner will simply pay much-reduced utility bills.
Ground-source heat pumps can be retrofitted in existing
homes that have traditional forced-air systems. In most
cases, the heat pump can be connected to the existing ductwork
while the loop system is installed outside in the ground
adjacent to the home.
In addition to the energy and cost savings associated with
geothermal energy systems, there may be special programs
(rebates or low interest loans) available through your
local electric utility to offset the initial installation
costs.
To get some idea of the potential
energy
cost savings for your new home construction project click the above link.
(http://earthcomfort.com/savings_calc.cgi)
Related websites include:
http://www.waterfurnace.com
http://www.climatemaster.com
2. The 10 Most Common Mistakes in Building Your New Home
This is the first in a
series from Mr. Chris McMinn. His firm, McMinn & Associates
are professional cost analysts and consultants. They review
and analyze a large range of residential and commercial construction
projects, applying the same methods and techniques of cost
engineering to residential construction projects as they
do for their commercial customers.
If you are looking for a professional cost consultant, we encourage you to contact
Chris. If you are looking for written Guide to many of the same issues Chris
points out, we encourage you to take a look at the House Building Guide.
The Fifth Pitfall...
Copyright © 2003 C. S. McMinn
Wait a moment, didn't we just read a previous article about this very topic?
You did. But as they say in real estate, the three biggies are: location, location,
location... In construction it's the same, only now it's: contractor, contractor,
contractor... So this is also part 2 of the fourth Pitfall: the process of finding
the right contractor for your project.
If you've been following these articles, you will reach a point where you have
(laboriously) acquired a list of contractors. This is something you've been developing
since day one. Your list should include at least ten contractors– preferably
more. You know about character, integrity and references. Now you've reached
the point where you need to get out there and look at their current and recently
completed projects.
You're also looking for contractors who tend to specialize in what you hope to
build. Aside from great references, if you're project is a new deck in your back
yard, or a bedroom addition, you need a small contractor. Someone who actually
works on the project themselves. Why? Because ideally, you want to match the
contractor to the task. Larger organizations, with an office, secretary and estimator,
will be (typically) less flexible and inclined to charge a higher percentage
for overhead. For a new home, you need a contractor with plenty of prior experience
in whole house construction.
But... here you are. Each of your prospective contractors has given you a list
of names and numbers. These are the owners of completed homes (or remodels).
No matter what it takes, you must now call each of them and ask for a guided
tour!
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Most homeowners are only too willing to share their
construction experiences. Even so, be discreet. New
homes and remodels usually expose our own ignorance.
Many homeowners will still be bruised from cost overruns
and mistakes they feel were at least partially their
fault. Some may be reluctant to invite you over.
In that case offer to take them out to lunch. It
is essential you have sufficient time to make friends,
discuss their project, examine their plans and– especially,
see their contract! You want to know how their original
bid worked out. Was the contractor fair and honest?
Did he charge for extras? What were they? How much
did they cost? What was the final cost compared to
the original bid? Why the increase?
Although these questions can be embarrassing to ask,
you will learn invaluable insights regarding contractors
and the construction process. You will see first
hand what each contractor delivers– and how
they interpreted their own contract.
Unless you have a lot of prior construction experience,
there is no substitute for this process. Take notes,
pictures... and listen. Ask if there were problems.
How were they resolved? Three interviews like this
for each contractor, and the lights will turn on.
You will begin to recognize attitudes and behavior
patterns, because...
behavior
never lies.
We do this all the time. What sounds really tedious
eventually becomes familiar– even easy. You
are looking for a great report on that contractor.
Ask each homeowner to rate their experience on a
scale of one to ten. Don't settle for anything less
than an eight. Seriously, I was speaking with a homeowner
last year, listening to their complaints about a
contractor they'd hired. On asking this question,
they rated him a "4". "But on the
next project", they said, "he was worse!"
